EGT E300td

[bonez59]

Hello
Ok my expencive Egt gauge in today as my other one i wasnt sure if it was reading right or not, So pulled the one from my race car, still in the same place straight after the turbo and only reading 350-370C that would explain why the engine is so loud on idle and up throught the revs.
Given it a service, fuel filter .......... when i changed the filter i turned it over and over and over, in the end i have to put a hand pump on the return pipe to pull the fuel through the filter.
Any ideas why it would be running lean/cool??

Thanks ian

 

[Alex Crow]

Diesels always run lean my friend, unless under full load.

 

[bonez59]

I know alex, this is under full load. and so as im off the full power the temp falls way to fast. Build a 360bhp nissan patrol for off roading so know all to well how the temps should be. Shame cant up the fueling by a turn of a screw in the pump. Be easy fix then
Should be seeing 650C if fueling about right.

 

[Dieselman]

still in the same place straight after the turbo and only reading 350-370C that would explain why the engine is so loud on idle and up throught the revs.

I don't understand your comment, why would running underfuelled make it loud.

Also the post turbo temps can't be relied on as an accurate indication, however if your engine really isn't fuelling up, then suspect the MAF output to be low.

Meter pin5 WRT Gnd.

 

[bonez59]

My understanding that if a diesel is running weak, they sound louder than normal, add fuel and they quiet down then the revs pick up. My idel is 500rpm,

Ok not being good with electrics, how i meter that? Volts?? Wrt? At idle, bringing the revs up and taking notes??

Thanks for more advice.

 

[Dieselman]

Connect the +ve lead to Pin 5 of the MAF by using a piece of wire, connect the -ve lead to Gnd and set the meter to 5v DC or the next range up.

Run the engine up in 500 rpm increments and record the voltage. This is best done under load of driving to account for the extra air consumed under boost.


You will end up with readings like this

 

[bonez59]

OK spot on. Thanks will try it tomorro

 

[Dieselman]

The MAF won't make any difference at idle, but check the EGR valve isn't wide open.

 

[Alex Crow]

My understanding that if a diesel is running weak, they sound louder than normal.....

They are running 'weak' nearly all the time, surprising that DM has not picked up on that!

Petrol engines have to run close to stochiometric all the time, and have a throttle valve to enable it.
Most diesels do not, and will be near 100/1 A/F ratio at idle - extremely 'weak',,, if you choose to call it that.

 

[Dieselman]

They are running 'weak' nearly all the time, surprising that DM has not picked up on that!

I have, it's a none issue here and not the cause for the noise.

Under full load the mixture is ~20:1, cruise ~50:1, idle ~100:1.

Noise is either timing too advanced, injector dribble or spray pattern, excessive EGR.

 

[bonez59]

was thinking of blanking off the egr, the car is laggy too, makes 1bar at 2500rpm. thought it should be on full boost 1200rpm. No boost leaks, turbo has no play, in or out, nor up or down. shame my wideband system does read high enough for a diesel, only goes up to 17:1, other wise id have that + egt as a aid.

 

[Dieselman]

1 Bar at 2500 rpm is healthy. It's never going to make full boost at 1200 rpm with a standard turbo, not unless you want it to fly to bits at 4000 rpm.

 

[bonez59]

really? shocked about that, i thought it was rubbish. Just thought it would be on it quick. Not used to a laggy diesel.

 

[Alex Crow]

I don't understand your comment, why would running underfuelled make it loud.....

You could have been clearer DM, diesels run 'underfuelled' as you put it 99.9 of the time.

 

[bonez59]

ok done the volt metre from pin 5 on the AFM and
idle 1.74v
full throttle
2000 2.95v
2500 3.33v
3000 3.56v
3500 3.74v
4000 3.86v
4500 3.86v

Thats on standard boost. about 1bar..

 

[Dieselman]

Compare that to my graph and you will see the MAF isn't recording full airflow. Looks like new MAF time.

 

[bonez59]

ok, found maf sensors for 74quid, but dont think they are bosch, foud bosch ones in germany for 135quid plus 5quid postage. Does that sound about right??

Out of interest, on the maf what pin number is the temp wire?

 

[Dieselman]

Out of interest, on the maf what pin number is the temp wire?

£135 is a good price.

There is no Temp on this MAf, but if there was it would be Pin-1.

 

[Dieselman]

Just before condemning the MAF check your meter accuracy as all your reasings seem low. Just meter the battery to check.

 

[bonez59]

ok will do thanks.